Method and a device for replacing incandescent filaments, and a lamp with several filaments

ABSTRACT

An automatic replacement circuit is provided for the replacement of burnt-out filaments as well as a method for implementing the replacement of incandescent filaments. The replacement circuit includes a pulse generator which operates independently of the activated filament to feed continuous feed pulses to a counter circuit while a separate resetting pulse circuit delivers resetting pulses to the counter unit in dependence on the current flowing through the filament. The resetting pulses cancel the feed pulses. In the absence of resetting pulses, the feed pulses accumulate and upon reaching a predetermined amount, trigger a trigger selector circuit for activating the next filament.

The invention relates to a method for supervising the function of theincandescent filament in connection with one or several incandescentlamps, which method comprises electronic controlled automatic replacingof a burnt-out filament for a new one. The invention also relates to acircuit for the automatic replacement of filaments, and an incandescentlamp with several filaments.

In connection with incandescent filaments or the like there is theproblem, that the service life of the individual incandescent filamentis relatively limited. When a filament, due to the transfer of metal,has burned out the whole lamp must be replaced. This causes economicalloss, because, in theory, only a substitution of the filament would benecessary, while other parts of the lamp, like the glass bulb and thegas filling could be utilized during a longer time. Provided with a newincandescent filament, the same lamp could serve until the transfer ofmetal from the incandescent filaments to the glass bulb gradually wouldcause a considerable loss of luminance. With the use of halogen gas,this transfer of metal to the glass can also be effectively prevented,but the transfer of metal from the filament irretrievable, results insome filament spots being thinner than the rest of the filament, atwhich spots the filament will burn through.

The replacement itself of a burnt-out lamp is no problem when the lampis in an easily accessible place. A lamp is, however, often situated ina rather difficult place, and then the cost of the labour needed for thereplacement is greater than the value of the lamp itself. Further, alamp often may be in such a use, that its light going out may causeinconvenience or even danger.

In order to avoid these inconveniencies a method according to theinvention is developed for replacing an incandescent filament. Inaddition, an automatic replacement circuit and a lamp with severalincandescent filaments are provided for utilizing this method.

Thus in accordance with the method, a pulse generating means independentof the function of the incandescent filament are made, for each caserespectively, to continually feed pulses to reference means having acertain storage capacity, which pulse storage is continually emptied bysignals from detecting means dependent upon the function of theincandescent filament. Any lack of such signals, e.g. due to a burn-outof the incandescent filament, will make the reference means full, whichin turn will cause the reference means to give a control signal to meansarranged for replacing the incandescent filament.

According to a preferred embodiment of the invention a 0-voltage circuitis used as a pulse generating means, which at each 0-point of analternating current gives a pulse to counting means working as areference means, and which continuously is emptied by a resetting pulsecircuit detecting the current passing through the incandescent filament,the counting means will fill up, and will give a signal to atrigger/selector circuit working as the means for changing saidfilament, and which in turns switches on connecting means arranged foreach of the several filaments. According to one embodiment of theinvention, triac-semiconductor means are preferably used as theconnecting means for each filament.

For the automatic replacement circuit according to the invention it ischaracteristic, that the circuit comprises a continuously working pulsegenerator, which is independent of the function of the incandescentfilaments, and a continuously working resetting pulse circuit, which isdependent on the function of the filaments, and further means forcomparing the pulses from the pulse generators, having means forreplacing filaments connected thereto.

The lamp according to the invention comprises a common socket and atleast one transparent closed shell connected thereto, having within theshell a gas for the protection of each respective incandescent meansignited on any occasion. According to the invention, the incandescentmeans of the lamp comprise several incandescent filaments, whichpreferably are used one at a time respectively, and which suitably areconnected at one end to a common terminal. The other end of each shuntarranged filament is connected to the automatic replacement meansarranged e.g. in the socket of the lamp. The replacement meansconnecting, in the manner described above, a new incandescent filamentinto operation when the previously working filament has burned out orceased to work for any other reason.

Now the invention will be discussed in more detail with reference to theenclosed drawings, where:

FIG. 1 shows a schematic view of the circuit according to the invention,

FIG. 2 discloses in detail the circuit diagram for an embodiment of theinvention, said embodiment having 8 incandescent filaments,

FIG. 3 shows a physical design of the circuit according to FIG. 2,

FIG. 4 shows a lamp with several incandescent filaments according to oneembodiment of the invention, and

FIG. 5 shows an alternative embodiment of a multi-filament lamp seenfrom above.

In the block diagram according to FIG. 2 the working principle of theinvention is generally shown. The figure discloses incandescentfilaments 1a. . . 1n of a practically arbitrary number. The number ofthe filaments is principally restricted only by the number whichtechnically can be fitted into one lamp. The central part of theautomatic replacement device is the reference (see FIG. 1), which in theembodiments according to FIGS. 2 and 3 is shown as a CMOS logic circuitIC2, e.g. of the type MC14520B, working as a counter. The counterreceives regular 0-pulses from a pulse generator 2 and simultaneously,when one of the incandescent filaments 1a. . . 1n is working, resettingpulses 6 from a detecting means 5.

The pulse generator 2, which in the embodiment according to FIGS. 2 and3 is shown as a zero voltage switch IC1, e.g. of the type UAA 10168,works essentially independently of the incandescent filaments when thepower is on, and feeds pulses 3 to the reference means 4 at the rate ofthe alternating current. In the embodiment according to FIGS. 2 and 3the zero voltage switch IC1 gives voltage/trigger pulses at every zeropoint in the alternating current.

When a filament is working a current 10 will pass, simultaneously withthe pulses 3, through a resetting circuit 5 working as a detectingmeans. When a filament is working, the resetting circuit, which in theembodiments according to FIGS. 2 and 3 is shown as a resetting pulsecircuit 51, also continuously feeds resetting pulses 6 to the referencemeans 4. Thus the reference means 4, or a counter 41 working as one,will be continuously emptied in spite of the continuous pulses 3 fromsaid pulse generator 2, and will hence not give any control signalshowing essential unbalance between signals 3 and 6, i.e. any signal 7urging a change of filament being sent to filament replacement means 8.

In the embodiment according to FIGS. 2 and 3 the resetting pulse circuit51 is shown as a circuit comprising a transistor Q1 (e.g. of the typeMMST 3906) and resistors R13, R14 and R15 (e.g. metal film resistors ofthe type MCR18J-2R2, -2R2 and -680R). The circuit generates pulses inevery second (negative) half cycle, and will thus see to a frequentenough resetting of the counter 41 (IC2), which cannot then be filled aslong as a current 10 through any of the filaments 1a. . . 1n flowsthrough the circuit.

When a filament 1a. . . 1n-1 in use ceases to work, the current 10through the detecting means 5 will be interrupted. The resetting signal6, which until then was essentially continuously given, will cease, andthe reference means 4, in the embodiment shown as the counter 41, willgradually be filled with signals 3 from the continuously working pulsegenerator 2 up to a predetermined amount. Then, the reference means 4,i.e. the counter 41 in the case shown, will give a control signal 7. Anysuitable counter component fulfilling the requirements of the functioncan be utilized as the counter 41. The counter 41 is always either emptyand filling up, or full, i.e. not full or full. The counter must be ableto give a signal 7 indicating, that the counter is full. The counter 41will be filled up with signals 3 from the pulse generator 2 only in thecase, that the detecting means 5, due to a burnt-out or the like of thefilament, does not continuously give resetting pulses 6. A signal"COUNTER FULL" from the counter can hence always be interpreted as aninstruction 7 to replace a filament.

When the replacement means 8 for replacing a filament receives a controlsignal 7 from the reference means 4, i.e. from counter 41, to replace afilament the replacement means 8 switches the power supply from thefilament 1a. . . 1n-1 which burned out or not working for is anotherreason, to a next incandescent filament 1a+1 . . . n. In the embodimentaccording to FIGS. 2 and 3 the filament replacement means 8 comprise aCMOS logic circuit IC3 with the reference 81, e.g. of type MC14051B. TheCMOS logic circuit acts as a trigger/selector and decides when whichincandescent filament 1a. . . 1n will glow. Preferably this isaccomplished through switching means 9a. . . 9n specific for eachfilament. In the embodiment according to FIGS. 2 and 3 the filamentspecific switching means 9a. . . 9n comprise triac-semiconductor meansT1 . . . T8 (e.g. of type 2N60773A).

In the embodiment shown in FIGS. 2 and 3 the resetting pulse circuit 51will be controlled by the very same current 10 passing through thefilament when the lamp is lit. If no current 10 passes, i.e. if thelight goes out when the lamp is connected to a fed voltage, indicatingthat a filament is burnt-out, no resetting pulse will come and thecounter 41 (IC2) will be filled. This leads then, to start with, to achange of triac and this way to a change of filament. When a current 10again passes through an incandescent filament, resetting pulses willcontinuously be originated (in every second half-cycle, i.e. 25pulses/sec), and so the counter 41 (IC2) cannot be filled up or changethe incandescent filament, but will keep the current in one and the samefilament.

The number of switching means 9a. . . 9n used depends upon the number offilaments and upon the characteristics of the replacement means 8respectively. In FIGS. 2 and 3 there is shown an embodiment having 8incandescent filaments, at which the number of the switchingtriac-semiconductors 9a. . . 9n also will be 8. If the number offilaments is greater than the capacity of the replacement means 8another replacement means with attached switching means can simply beconnected after the first one. Instead of the triac-semiconductorcircuit shown also other switching means can be utilized as theswitching means 9a. . . 9n. According to an advantageous embodiment ofthe invention a special indicating means is connected to the changingmeans 8 in addition to the switching means 9a. . . 9n, which indicatingmeans give an alarm outside the lamp when a certain predetermined numberof filaments have burned out.

The other components shown in FIGS. 2 and 3 serve for the adaptation ofthe main components. The values for the adaptation components will bechosen according to the actual mains voltage, the effect of theincandescent filaments used and other such variables, respectively.

The method and arrangement according to the invention for replacingincandescent filaments can be utilized, as such, for connecting, inturn, several normal incandescent lamps with one incandescent filament.Simply, in such a case a shunted lamp will be connected instead of thelamp which has burned out.

However, a lamp arrangement with several individual lamps will needseveral shunted lamps, each with it own mounting socket, respectively,and hence all of the invention's advantages cannot be achieved with suchan arrangement. For this reason the invention also relates to a speciallamp, having several incandescent filaments 1a. . . 1n connected to thesame socket 11. Thus the filaments, as shown in FIGS. 4 and 5, can beplaced in one common gas space 12, i.e. all filaments can exist in aspace defined by a common shell 13. Then the filaments can be arrangede.g. one above the other, as shown in FIG. 4, or in a star-likearrangement according to FIG. 5, and arrangements combining thesestructures can also be considered.

The incandescent filaments 1a. . . 1n can also be arranged so, that forevery filament 1i there is a gas space closed around the filament,respectively, defined by a shell 13 being either separate or formed by atransparent isolating wall common with another filament. An advantage ofa separate gas space for each filament is, that the vaporization ofmetal occurring in connection with any working incandescent filamentsdoes not have any influence upon the function of other filaments. Theseparate gas spaces can, within the concept of the invention, bearranged in lines, in an arch, as a cluster or in any other shape, e.g.for indicating the lamp's lifetime.

In the embodiment shown all the individual filaments 1a. . . 1n areconnected to a common terminal 15, but the filaments can also beinterconnected in other ways so, that each individual filament 1i can beindividually connected to work in such a manner, that the current 10through the lamp can be detected with said detecting means 5.

I claim:
 1. A method for supervising the function of incandescentfilaments (1a. . . 1n) in connection with one or several incandescentlamps, which method comprises electronic controlled automaticreplacement of a burnt-out filament (1i) by a new one (1j),characterized in, that pulse generating means (2) independent of thefunction of said incandescent filament (1a. . . 1n) are made tocontinually feed pulses (3) to reference means (4) having a certainstorage capacity, the pulse store of which is continually emptied bysignals (6) from detecting means (5) dependent on the function of saidincandescent filament (1a. . . 1n), whereby any lack of such signals (6)will make said reference means (4) full, so that said reference means(4) is caused to send a command signal (7) to replacement means (8) forreplacing said incandescent filament (1a. . . 1n).
 2. A method accordingto claim 1, characterized in, that a zero voltage circuit is used assaid pulse generating means (2), which circuit at every zero point in analternate current gives a pulse to a counter (41) working as saidreference means (4), and which is continuously emptied by a resettingpulse circuit (51) continuously detecting a current (10) through saidincandescent filament (1a. . . 1n), whereby a discontinuance of saidcurrent (10) through said filament (1a. . . 1n) causes said counter (41)to fill up and thus to generate a signal (7) to a trigger/selectorcircuit (81) working as said reference means (8) for said filament (1a.. . 1n), and which in turns connects switching means (9a. . . 9n)specific for each filament.
 3. A method according to claim 1 or 2,characterized in, that triac-semiconductor means are used as switchingmeans (9a. . . 9n) specific for each filament.
 4. A lamp arrangementcomprisinga plurality of incandescent filaments; replacement means forselecting and triggering one of said filaments for passage of a currenttherethrough; a pulse generator for emitting feed pulses independentlyof the operation of said filaments during passage of current through aselected filament; detecting means for emitting resetting pulses independence on the passage of current through said selected filament; andreference means connected to said pulse generator to receive and storesaid feed pulses up to a predetermined amount, said reference meansbeing connected to said detecting means to receive said resetting pulsesfor cancellation of said feed pulses stored therein, said referencemeans being connected to said replacement means to deliver a controlsignal thereto in response to storage of said predetermined amount offeed pulses for selecting another filament for passage of the currenttherethrough.
 5. A lamp as set forth in claim 4 wherein said replacementmeans is a trigger selector circuit.
 6. A lamp as set forth in claim 4wherein said detecting means is a resetting pulse circuit.
 7. A lamp asset forth in claim 4 wherein said reference means is a counter circuit.8. A lamp as set forth in claim 4 which further comprises a plurality ofswitching means, each switching means being connected between and tosaid replacement means and a respective filament.
 9. A lamp as set forthin claim 8 wherein each switching means is a triac-semiconductor means.10. A lamp as set forth in claim 4 wherein said filaments are connectedin parallel.
 11. A lamp as set forth in claim 4 wherein said pulsegenerator emits said feed pulses at a rate of alternating currentdelivered to the selected filament.
 12. A lamp as set forth in claim 11wherein said detecting means emits said resetting pulses in every secondhalf cycle of the current delivered to the selected filament.
 13. A lampas set forth in claim 10 further comprising a shell housing saidfilaments and a socket mounted said shell in gas-tight relation andhousing at least said replacement means therein.
 14. A circuitcomprisinga plurality of incandescent filaments; a trigger selectorcircuit for selecting a respective one of said filaments for passage ofa current therethrough; a pulse generator for emitting feed pulsesindependently of the operation of said filaments during passage ofcurrent through a selected filament; a resetting pulse circuit foremitting resetting pulses in dependence on the passage of currentthrough said selected filament; and a counter circuit connected to saidpulse generator and said resetting pulse circuit to receive said feedpulses and said resetting pulses and to store feed pulses in excess ofsaid resetting pulses up to a predetermined amount, said counter circuitbeing connected to said trigger selector circuit to deliver a controlsignal thereto in response to said predetermined amount of feed pulsesbeing stored for selecting another filament for passage of the currenttherethrough.
 15. A circuit as set forth in claim 14 wherein said pulsegenerator emits said feed pulses at a rate of alternating currentdelivered to the selected filament.
 16. A circuit as set forth in claim14 wherein said resetting pulse circuit emits said resetting pulses inevery second half cycle of the current delivered to the selectedfilament.
 17. A circuit according to claim 20 wherein said pulsegenerator is a zero pulse generator operating on an alternating current,and said resetting circuit is connected for continuously sensing acurrent passing through any operating incandescent filament in such amanner, that said current simultaneously continuously causes resettingpulses to be fed to said counter circuit, whereby a discontinuance insaid resetting pulses will cause said counter circuit to fill up andsaid control signal to be given to said trigger selector circuit forreplacing a selected incandescent filament.
 18. A circuit according toclaim 6 wherein said trigger selector circuit comprises a CMOS logiccircuit and filament specific semiconductor circuits triggered one at atime by said trigger selector circuit.